Safety stop for roll-up door



March 24, 1959 E. J. MANLEY SAFETY STOP FOR ROLL-UP DOOR 3 Sheets-Sheet 1 Filed Feb. 9, 1956 INVEN TOR. 5011 1170 .1 M/I/Vlfy March 24, 1959 E. .1. MANLEY SAFETY STOP FOR ROLL-UP DOOR 3 Sheets-Sheet 2 Filed Feb. 9, 1956 I I I I 1 1; 1

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Hlllllll Illllllll r & INVENTOR. Q 1M140 AMA My ,ws ATTOQ/VEY United States Patent SAFETY s'ror FOR ROLL-UP DOOR Edward J. Manley, Yardley, Pa, assignor to United States Steel Corporation, a corporation of New Jersey Application February 9, 1956, Serial No. 564,540

6 Claims. (Cl. 160189) This invention relates to overhead rolling steel doors and, more particularly, is directed to an improved door raising and lowering drive which provides a safety stop for preventing uncontrolled gravitational movement of a door to its lowered position.

Overhead or roll-up doors of the large sizes used in industrial establishments are generally provided with a motor operated drive for effecting their movement between raised and lowered positions. To facilitate opening and closing movements and to reduce power requirements of the drive, the doors are counterbalanced by springs which are wound during lowering movement to closed position and which unwind to assist raising the door to open position. The counterbalance springs, due to repeated winding and unwinding, frequently fail during raising and lowering movements of the door and this causes sudden excessive loading of the door drive mechanism. When a door drive mechanism fails under a load of this character, the door operated thereby is released for gravitational movement to closed position. industrial doors may have a weight in excess of /2 ton, such uncontrolled gravitational door movement is hazardous to personnel or equipment under the door.

One of the principal objects of this invention is to provide a safety stop for preventing an uncontrolled gravitational closing movement of an overhead rolling steel door in response to failure of its counterbalancing spring and operating drive.

A further object is to provide a drive for raising and lowering a counterbalanced load with a safety stop for stopping lowering movement of the load under conditions rendering the downwardly moving load effective to impart motion to the drive.

A still further object is to provide a drive of the character referred to with a stop in the form of a ratchet mechanism which is normally inoperative to interfere with load raising or lowering operations of the drive but which is rendered operative to stop the drive and thereby lowering movement of the load in response to load conditions tending to impart motion to the drive.

Another object of the invention is to provide a ratchet mechanism for controlling the operation of a drive for overhead roll-up doors with a means for rendering it inoperative to stop a door lowering movement by the drive and for rendering it operative to stop door closing movement both when such closing movement takes place independently of its drive and upon failure of its drive.

Other objects and advantages of the invention will be apparent from the following description.

In the drawings, there is shown a preferred embodiment of the invention. In this showing:

Figure 1 is a partial front elevational view of an overhead steel roll-up door and in which parts are broken away and shown in section to illustrate the construction of the door reeling mechanism;

Figure 2 is a sectional view taken along the line HI.l of Figure 1 and in which the roll-up door is shown diagrammatically by broken lines;

Since during raising movement of the door.

Figure 3 is a sectional view of a portion of the drive shown in Figure 1, parts of the drive being shown in side elevation;

Figure 4 is a sectional view taken substantially along the line IVIV of Figure 3; and

Figure 5 is a sectional and elevational view taken substantially along the line VV of Figure 1.

Figures 1 and 2 show a conventional type of roll-up door which is formed of steel slats 1 pivotally connected together along adjacent edgesso that the door may be raised and lowered by winding and unwinding on a reel 2. The ends of the slats 1 are arranged in guides 3 which are secured to the door jambs 4 and guide the vertical movement of the door as it is wound and unwound on the reel 2, the path of reeling movement of the door slats 1 being indicated by the broken line also designated by the numeral 1 in Figure 2. The reel 2 is mounted in an enclosure or housing 5 and comprises a pipe 6 on which rings 7 are secured. The end slat 1 of the door is secured to the rings 7 as at 8 in such manner that each ring 7. forms a drum on which the door is reeled. Operation of the reel 2 is effected by a drive shaft 10 which has a keyed connection with a plug 11 in one end of the pipe 6 and a bearing support at 12 in one end of the housing 5. The other end of the pipe 6 is rotatably supported by a plug 13 on a shaft 14 which is provided with a bearing support 15 in the other end of the housing 5. The outer end of the shaft 14 is locked against rotation by a wheel 16 and locking detent 17. The inner end of the shaft 14 is connected to one end of a counterbalancing spring 18 which has its other end connected to a pin 19 secured in the pipe 6.

Rotation of the pipe 6 in a counter-clockwise direction as viewed in Figure 2 is effective to wind the door slats 1 on the reel drums 7 and to move the door to its raised or open position. Rotation of the pipe 6 in a clockwise direction effects unreeling of the slats 1 and moves the door to its lower or closed position. Movement of the door to and from its open and closed positions is counterbalanced by the spring 18 which is wound during lowering movement and which unwinds In conventional arrangements of this type of door, the shaft 10 is driven by a chain and sprocket drive which is subjected to sudden and excessive loading upon breakage of the counterbalancing spring 18. Failures of the counterbalancing springs 18 are frequent and generally cause failure of the chain and sprocket drives. This in turn releases the door for free and unrestrained gravitational movement to its lowered position.

The drive of this invention is designated as a whole by the numeral 20 and, as best shown in Figure 3, is apscribed. The driven member 23 comprises a hub 24 which is keyed on the shaft 10 and has a pair of axially spaced flanges 25 secured thereto and projecting radially outwardly therefrom. Each of the flanges 25 has a slot 26 of arcuate shape through which a drive pin 27 pro- I jects. The drive pin 27 is secured to an assembly com- 31and 32 of the slot 26 render the sprocket wheel 22 positions in which the drive pin 27 has driving engage- I ment with the ends 31 and 32 of the slot 26. Movement of the drive pin 27 into engagement with the ends effective as a drive or driving member to impart motion in opposite directions to the driven member 23 and the shaft for effecting raising and lowering movements of the door. As best shown in Figures. 1 and 5, the sprocket 22 is operated by a sprocket chain 33 which in turn is operated by a sprocket 34 having a motor 35 for operating it in reverse directions. The assembly of the sprocket wheel 22 and its hub 29 is secured against axial movement on the hub 24 by an end plate 36 which is secured to the hub 24 by bolts 37.

A ratchet mechanism is provided for controlling rotation of the driven member 23. It comprises a stationary internal ratchet wheel 41 which is secured by bolts 42 to the housing end plate 21 and a ratchet pawl 43. The pawl 43 is pivotally supported in the space between the flanges by a pin 44 which has its ends rotatably supported in the flanges 25. A spring 45 provides a bias for pivotally moving the pawl 43 in a counter-clockwise direction to the position shown in Figure 4 in which it has ratcheting engagement with the ratchet teeth 46 on the ratchet wheel 41. The spring 45 has one end bearing against an operating arm 47 extending outwardly from the body of the pawl 43 and its other end bearing against a pin 43 extending transversely of the space between the flanges 25. It is mounted on a guide pin 49 which has one end secured by a set screw 50 in the pin 48 and its other end projecting into an opening 51 in the pawl arm 47. The spring 45 biases the pawl 43 to a position with its cam surface 52 engaged with a stationary cam surface 53 on a stationary ratchet tooth 46. Upon rotation of the driving member in a counter-clockwise direction as viewed in Figure 4, the pawl 43 has a ratcheting movement over the ratchet teeth 46, engagement of the cam surfaces 52 and 53 being effective to pivot the pawl 43 against the action of its biasing spring 45. In the position shown in Figure 4, the pawl 43 is effective to prevent rotational movement of the driven member 23 and shaft 10 in a clockwise direction, such movement being prevented by engagement of a curved stop surface 55 on the pawl 43 with a stop surface 56 on one of the ratchet teeth 46. The surfaces 55 and 56 have a similar radius of curvature about the axis of the pin 44 when in locking engagement so that the pawl 43 may be rotated to and from an operative locking position.

Movement of the pin 27 in the arcuate slots 26 is utilized to move the pawl 43 to an inoperative position and to hold it from movement into ratcheting engagement with the ratchet wheel 41 when the member 23 is actuated in a clockwise direction by the sprocket wheel 22 to impart a lowering movement to the door. This control is effected by a link 60 having a hook 61 at one end which is engaged over the pin 27 and a pivot 62 at its other end connecting it to ears 63 projecting outwardly from the pawl 43. A pin 64 acts as a stop for maintaining the link 60 in an operative position with respect to the drive pin 27. When the drive pin 27 is rotated by the sprocket wheel 22 to effect a door lowering movement, the pin 27 moves to the end 31 of the slot 26, and this movement causes the link 60 to rotate the pawl 43 in a clockwise direction as viewed in Figure 4 to a position out of ratcheting engagement with the ratchet teeth 46. As long as the pin 27 continues to drive the member 23 in this manner, the pawl 43 will be held out of operative engagement with the ratchet wheel 41, and the ratcheting mechanism will be ineffective to interfere with a door lowering movement. In the event that the driven member 23 overruns its drive sprocket 22, as will happen when the sprocket drive fails after failure of the counterbalance spring 18 and lowering movement of the door imparts rotation to the member 23 through the drive shaft 10, the drive pin 27 will move relatively toward the end 32 of the slot 26 and render the pawl biasing spring 45 effective to move the pawl 43 to a position with its surface 55 engaging a ratchet stop surface 56. Movement of the surfaces 55 and 56 into engagement with each other in this manner will be effective to stop further rotation of the member 23 and thus discontinue lowering movement of the door.

From the foregoing, it will be apparent that lowering movement of the door cannot be effected unless the drive 20 from the motor 35 is in operation. If the drive 20 is in operation and the door moves downwardly at a faster speed than called for by the motor 35, the pawl 43 will move into locking engagement with the ratchet teeth 46 and remain there until disengaged by a motor actuated movement of the drive 20. Attention is particularly directed to the fact that the responsiveness of the pawl 43 to the operating condition of drive 20 is effected in part by providing for relative angular movement of the sprocket 22 and the drive member 23 for the shaft 10. Upon operation of the drive 20 in reverse directions, the driving member or pin 27 moves to opposite ends 31 and 32 of the slot 26 and this relative movement controls operation of the pawl 43 which, being spring loaded, is forced into locking engagement when the door driving force applied to the pin 27 is interrupted.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a roll-up door assembly including a door mounted for movement between raised and lowered positions and a counterbalancing coil spring providing a resilient bias against movement of said door to its lower position, a safety drive for moving said door to said positions and for preventing its uncontrolled movement by gravity to .said lowered position upon failure of said counterbalancing spring comprising a driven member movable in one direction for moving said door toward its raised position and in an opposite direction for moving said door toward its lowered position, a reversible driving member for driving said driven member in both of said directions,

means for stoppng the movement of said driven member in said opposite direction to stop the movement of said door toward said lowered position, and means controlling the operation of said stopping means including means for rendering it inoperative in response to movement of said driven member in said opposite direction by said driving member and means for rendering it operative in response to rotation of said driven member in said opposite direction by said door.

2. In a roll-up door assembly including a door mounted for movement between raised and lowered positions and a counterbalancing coil spring providing a resilient bias against movement of said door to its lower position, a safety drive for moving said door to said positions and for preventing its uncontrolled movement by gravity to said loweredposition upon failure of said counterbalancing spring comprising a rotatable member having a mechanical connection with said door for rotation in opposite directions respectively in response to movement of said door toward different ones of said positions, a stationary ratchet wheel arranged concentrically of said rotatable member, a ratchet pawl mounted on said member for movement into and out of ratcheting engagement with said ratchet wheel, said ratchet pawl and wheel when in ratcheting engagement being effective to provent rotation of said member in the one of said opposite directions corresponding to lowering movement of said door but permitting its rotation in the other of said directions corresponding to raising movement of said door, a driving member for rotating said rotatable member, and means responsive to rotation of said rotatable member in said one direction by said driving member for holding said pawl against movement into ratcheting engagement with said ratchet wheel and to its rotation by said load through said mechanical'connection for releasing said pawl for movement into ratcheting engagement with said wheel.

3. In a roll-up door assembly including a door mounted for movement between raised and lowered positions and a counterbalancing coil spring providing a resilient bias against movement of said door to its lower position, a safety drive for actuating said door to said positions and for preventing its uncontrolled falling movement to said lowered position upon failure of said counterbalancing spring comprising a drive shaft rotatable in one direction to raise said door and in an opposite direction to lower said door, a drive member mounted on said shaft for rotation therewith, a stationary ratchet wheel mounted concentrically of said drive member, a ratchet pawl mounted on said drive member for movement into and out of ratcheting engagement with said ratchet wheel, said ratchet wheel and pawl being efiective when in ratcheting engagement to hold said drive member and shaft against rotation in said opposite direction but permitting their rotation in said one direction, a driving member mounted for angular movement between two operating positions relative to said drive member, means interconnecting said driving and drive members and rendering said driving member operative to rotate said drive member in opposite rotational directions respectively upon movement to its said operating positions, and means for holding said pawl out of ratcheting engagement with said ratchet Wheel in response to relative angular movement of said driving member into the one of its said two operating positions in which it is operative to rotate said drive member and shaft in said opposite direction to lower said door, said holding means including means rendering it inoperative upon relative angular movement of said driving and drive members out of said one operating position.

4. The invention defined in claim 3 characterized by said interconnecting means comprising a crank pin secured to said driving member, and said drive member having an arcuate slot in which said crank pin is received.

5. The invention defined in claim 4 characterized by said pawl holding means comprising a link having a pivotal connection with said pawl and a part lying in the path of movement of said crank pin through said slot so that it is operated by movement of said pin in said slot.

6. In a roll-up door assembly including a door mounted for movement between raised and lowered positions, a shaft rotatable in one direction for operating said door to its raised position and in an opposite direction for operating said door to its lowered position, and a door counterbalancing coil spring providing a resilient 'bias against rotation of said shaft in said opposite direction, the combination therewith of a safety drive for operating said shaft comprising a drive member keyed on said shaft and having an arcuate slot therein, a drive sprocket wheel supported for rotation relative to said shaft and having a crank pin projecting into said slot for movement to positions at opposite ends thereof in which it provides driving connections between said sprocket wheel and drive member, and means for preventing rotation of said shaft in said opposite direction by the weight of said door upon failure of said counterbalancing spring comprising a stationary ratchet wheel mounted concentrically of said drive member, a ratchet pawl mounted on said drive member for movement into and out of ratcheting engagement with said ratchet wheel, said ratchet wheel and pawl being effective when in ratcheting engagement to hold said drive member and shaft against rotation in said opposite direction but permitting their rotation in said one direction, and means responsive to movement of said crank pin to the end of said slot in which it provides a driving connection for rotating said driving member and shaft in said opposite directon for moving said pawl out of ratcheting engagement with said ratchet wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,700,864 Tredway Feb. 5, 1929 2,020,831 Greegor Nov. 12, 1935 2,097,242 Robinson Oct. 26, 1937 2,099,191 Blodgett Nov. 16, 1937 

